The proposed research is aiming at i) developing new and effective methods for the asymmetric synthesis of beta-lactams and azetidines based on addition-cyclizations and cycloadditions: By means of the effective methods developed, a variety of chiral synthetic building blocks for peptide analogs, poly-beta-lactams, and polyazetidines will be synthesized: These new methods are also beneficial to the synthesis of beta-lactam antibiotics in general, ii) synthesizing "deoxo" analogs of brain peptides and labelled peptides for neurobiological studies using the "azetidine synthon method" and "beta-lactam synthon method": The behavior of new "deoxo" analogs of enkephalin and vasopressin toward enzymatic degradation in the brain will be studied: A new method for the stereo- and regiospecific labelling of peptides will be developed and established using a stereospecific cleavage of beta-lactam with tritium or deuterium, iii) synthesizing chiral cyclic poly-beta-lactams and polyazetidines as potential ionophores or reagents for endonucleolytic cleavage of DNA; metal ion binding ability of these chiral heterocyclic ligands will be investigated and several metal complexes will be synthesized, which are expected to intercalate into double-strand DNA and cleave it, and iv) biological study and biological activity screening in collaboration with a neurobiologist, a biochemist and the institutions which have excellent testing facilities.